Early Cat. Converter Failure (2014 GM 5.3)

[Packer12]

Hi there, long time lurker, first time poster.

I purchases a certified used 2014 Chevy Silverado 1500 5.3L from a Chevy dealership with 63,000 miles. At 68,000 miles I start having rough starts, occasional misfiring, slow throttle response and a CEL. So I take it to the Chevy dealership and they ended up replacing the catalytic converters under warranty. That made a huge difference and everything is back to normal now. I don't think the dealership was trying to hide anything when I bought it because throttle response and everything was fine at purchase.

However, my question is: what would cause the Cats to fail this early? These new gen V small block (L83) engines have DI so perhaps that could have something to do with it? The dealership implied that they have replaced a few Cats on the '14's but otherwise they have been really solid trucks.

Thanks in advance!

 

[NHGUY]

Sounds like it plugged.Probably had a severe misfire in the past and that problem was solved but the damaged converter remained.

 

[gathermewool]

What was the fault code?

 

[Packer12]

I can't remember the code, but yes it was clogged. I know the previous history of where the truck came from and I don't think bad gas was an issue. But there's usually a reason cats get clogged, I just don't know what could have caused it so early...

 

[Tegger]

Originally Posted By: Packer12
there's usually a reason cats get clogged, I just don't know what could have caused it so early...

One big reason is repeatedly running the gas-tank level very low.

 

[Wolf359]

Could just be bad manufacturer. I had a Ford Contour once where the cats got clogged and they were replaced under warranty, a little while later they had a recall and they replaced the cats again. Hope your replacement ones last a while, I think federal emissions is only 8/80k, unless the car is a Pzev, then it's 15/150k, but I doubt it as Idaho isn't a Pzev state.

 

[itguy08]

Originally Posted By: Tegger

One big reason is repeatedly running the gas-tank level very low.

Unless you are constantly running out of gas, that's an old wive's tale.

 

[Wolf359]

Originally Posted By: itguy08
Originally Posted By: Tegger

One big reason is repeatedly running the gas-tank level very low.

Unless you are constantly running out of gas, that's an old wive's tale.


Yeah, that makes no sense either. Usually a very low tank leads to a burned out fuel pump.

 

[rubberchicken]

Originally Posted By: Wolf359
Could just be bad manufacturer. I had a Ford Contour once where the cats got clogged and they were replaced under warranty, a little while later they had a recall and they replaced the cats again. Hope your replacement ones last a while, I think federal emissions is only 8/80k, unless the car is a Pzev, then it's 15/150k, but I doubt it as Idaho isn't a Pzev state.


I had a similar problem with a 1998 Contour, v6- the cats next to the cylinder banks (i.e. manifold cats) tended to cause error codes: eventually Ford came out with a new ECU flash and mostly resolved the problem.

 

[demarpaint]

Originally Posted By: NHGUY
Sounds like it plugged.Probably had a severe misfire in the past and that problem was solved but the damaged converter remained.


That's what I think. They could have been driving around with a bad plug or coin pack for a while, got it fixed and the CC died later as a result.

Does the engine use oil?

 

[Lubener]

The cat should last nearly the life of the vehicle. Its failure is a symptom of engine problem.

 

[JetStar]

Never experienced a plugged cat, cracked and rattling at >100K miles, but never plugged, seems odd that it would fail that early without a contributing factor. I like to go WOT once in a while to keep them burned off.

 

[Rob_Roy]

The same thing happened to my friends 2004 Silverado when it was ~3 years old. He only lived about 2 miles from work, and the dealership suggested that the short trips were to blame. Not sure if that is true, but he ended up getting a beater to drive to work and saved the truck for longer trips. He kept the truck until 2016 and never had another issue.

 

[Packer12]

Over the last OCI, about 7,000 miles (90hi/10city) it used about 1 quart.

It is used mainly for highway trips on the weekends and only used in town driving a couple times a week. The clogged cat problem started once it started getting colder. It does see below 0°F starts so maybe it runs too rich and that could be what caused it. The dealership said they have replaced a few. Either way, once my warranty is up I plan on installing a catch can to prevent all that gunk from going in my engine and keep carbon deposits on the intake valves at a minimum.